The use of delivery devices or introducers employing catheters has long been known for a variety of medical procedures, including procedures for establishing, re-establishing or maintaining passages, cavities or lumens in vessels, organs or ducts in human and veterinary patients, occlusion of such vessels, delivering medical treatments, and other interventions. For these procedures, it has also long been known to deliver an implantable medical device by means of a catheter, often intraluminally. For example, a stent, stent-graft, vena cava filter or occlusion device may be delivered intraluminally from the femoral artery for deployment.
For procedures in which a prosthesis or other medical device is implanted into a patient, the device to be implanted is normally held on a carrier catheter or cannula of the introducer in a compressed state and then released from the carrier catheter so as to expand to its normal operating state, prior to withdrawal of the catheter from the patient to leave the implant in position.
A variety of delivery devices or introducers is known in the art. These generally involve positioning the implantable medical device on a distal part of a delivery device, that is, at an end furthest from the external manipulation end used by the clinician during the deployment procedure. The implantable medical device is normally held at the distal end of a carrier catheter of the device by a suitable restraining mechanism, which may include restraining wires or trigger wires. It is also conventional for the introducer assembly to include an outer sheath to cover the implant in order to protect the medical device and also the patient's vasculature or organs during the delivery process. Once the medical device has been positioned at the location in which it is to be released, the sheath is retracted along the carrier catheter to expose the medical device. The medical device is then expanded, either automatically, if the device is of the self-expanding type, or by a suitable expanding mechanism if not, such as by means of an expansion balloon.
Many endoluminal medical devices are radially self-expanding. Radially self-expanding devices are advantageous because they do not require complicated and bulky balloon catheter systems for deployment. Such devices present a challenge, however, in that once one end of the device is released and anchored into the body lumen, subsequent positioning can be difficult. This is particularly the case if the ends of the device include anchoring mechanisms to secure the prosthesis to the body lumen. As a consequence, many deployment devices have been proposed that allow the self-expanding medical device to be partially expanded while providing a mechanism for retaining the proximal and distal extremities of the device until the main part of the device has been properly positioned.
WO 2004/028399 discloses a stent graft deployment device for release of a distal end of a stent graft before its proximal end. The device includes a sliding handle to which the deployment catheter and a retention section or capsule are fixed mounted on a fixed handle associated with a trigger wire release mechanism. The sliding handle can slide longitudinally with respect to the fixed handle.
WO 2005/032425 discloses an introducer including a retention section for retaining a proximal end of the prosthesis thereto. The proximal end of the prosthesis is retained by a trigger-wire. The trigger-wire can be removed from the introducer to release the proximal end of the prosthesis into the body lumen.
WO 2005/037142 discloses another introducer for an expandable endovascular prosthesis. The introducer includes a retention section for retaining a proximal end of the prosthesis thereto, similar to that of WO 2005/032425.
U.S. Pat. No. 6,866,669 discloses a device for retracting an outer sheath in which there is provided, as one of two retraction mechanisms, a threaded shaft connected to the outer sheath, which can be controlled by rotation of a knurled knob.
U.S. Pat. No. 6,402,760 discloses a system which uses a motorised unit to retract a sheath.
U.S. Pat. No. 5,776,142 discloses an arrangement in which inner and outer catheters are attached to respective handle portions, which handle portions are connected to one another by means of a threaded element. Withdrawal of the sheath relative to the inner catheter is achieved by twisting the handles relative to one another.
WO 98/20811 discloses a system in which retraction of a sheath is achieved by movement of a slider in a longitudinal direction of a handle.
WO 00/67675 also discloses a longitudinally moveable actuator for withdrawing an outer sheath, provided with a locking mechanism.
DE 44 20 142 discloses a handle attached to an applicator having two guides for axial relocation of a transfer tube. One guide moves the transfer tube back. The other guide is fixed to the handle and locks the transfer tube when the first guide is moved forwards.
One problem with known deployment systems is that in order to deploy an implant correctly within a patient, different deployment steps need to be taken in a very specific order. The surgeon or clinician must be very careful to carry out the steps in the required order; mistakes could result in an abortive procedure and possible injury to a patient. Current handles include a number of components that must be removed by the surgeon during the deployment procedure. These components then need to be discarded.